This invention relates to IC cards and mating sockets of free insertion and withdrawl capability. In the prior art it is commonly known that information memory cards magnetically store information and are being used between banking and other facilities and their customers. The card of this type, the so called magnetic card, is convenient in its own use and is considered to be the only kind of memory card for this application. However the greatest weak point of this type of card is that the amount of information that can be stored thereon is very limited. Also it can furnish information only in response to requirements from outside equipment and does not have logical and calculating functions of its own. In order to eliminate these problems the IC card of the present invention was devised. The present invention also solves interfacing problems by providing an interconnection structure which is inexpensive and can be manufactured in small sizes on thin type cards which contain units such as a battery, a memory, a central processing unit, switches, etc., both active and passive elements. The purpose of this invention is to furnish an IC card and mating socket which is small and thin sized and free from the various weaknesses described above and to facilitate interconnection between the IC card and mating socket.